Backpack-type air blowing working machine

ABSTRACT

Disclosed is a backpack-type air-blowing working machine in which a volute casing incorporating a centrifugal fan configured to be driven by an electric motor is assembled in an upstanding manner to a backpack frame to be carried on the back of an operator using shoulder straps during use. The backpack-type air-blowing working machine includes a rechargeable battery pack connected to the electric motor and detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below a rotation axis of the centrifugal fan, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of a rear end of the volute casing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2016/061754 filed Apr. 12, 2016, claiming priority based onJapanese Patent Application No. 2015-086176 filed Apr. 20, 2015,Japanese Patent Application No. 2015-086173 filed Apr. 20, 2015, andJapanese Patent Application No. 2015-086171 filed Apr. 20, 2015, thecontents of all of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention relates to a backpack-type air-blowing workingmachine for use in cleaning small pieces such as fallen leaves or mowngrass, and more particularly to a backpack-type air-blowing workingmachine in which a volute casing incorporating a centrifugal fanconfigured to be driven by an electric motor is assembled to a backpackframe.

BACKGROUND ART

U.S. Pat. No. 6,006,400 discloses a backpack blower which comprises: avolute casing mounted to a cross-sectionally L-shaped backpack frame tobe carried on the back of an operator (i.e., a user or a worker); acentrifugal fan rotatably pivoted within the volute casing; an electricmotor assembled to a rear side of the volute casing and operable torotate the centrifugal fan, and a battery attached to a lower horizontalframe portion of the backpack frame. This backpack blower is configuredsuch that the centrifugal fan in the volute casing is rotated by theelectric motor operated by electric power fed from the battery, and airsucked into the volute casing according to the rotation of thecentrifugal fan is blown out from a blowout port of the volute casing.

In the backpack blower, the large-size electric motor is disposed behindthe volute casing, and attached to a longitudinally intermediate regionof the lower horizontal frame portion of the backpack frame. Therefore,an operator carries the backpack frame of backpack blower on his/herback using shoulder straps during use, a position of the center ofgravity of the backpack blower will lie relatively rearward y, so thatthe operator is likely to fall down rearwardly, leading to difficulty incleaning work.

Moreover, the battery for feeding electric power to the electric motoris fixed to the lower horizontal frame portion of the backpack frame bya screw through a bracket. This means that the backpack blower is notdesigned supposing that the battery is frequently detached and charged.Therefore, for charging the battery, it is necessary to carry thebackpack blower to a vicinity of a power supply, or to detach thebracket for each charging operation. Thus, it is necessary to take timeand effort for the battery charging operation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a backpack-typeair-blowing working machine capable of eliminating the above difficulty.Specifically, according to a first aspect of the present invention,there is provided a backpack-type air-blowing working machine whichcomprises: a backpack frame having at least a back plate portionconformable to the back of an operator, wherein the backpack frame isconfigured to be carried on the back of the operator through the backplate portion using shoulder straps; a volute casing mounted to thebackpack frame at a position rearward of the back plate portion, in sucha manner that a center of a volute is set in a direction intersecting aplanar direction of the back plate portion; a centrifugal fan rotatablysupported within the volute casing; an electric motor assembled to thevolute casing and operable to rotate the centrifugal fan; and arechargeable battery pack attached to the backpack frame and operable tofeed electric power to the electric motor, wherein the backpack-typeair-blowing working machine is configured such that a position of thecenter of gravity of the backpack-type air-blowing working machine asviewed from the rear thereof located below a rotation axis of thecentrifugal fan, and a position of the center of gravity of thebackpack-type air-blowing working machine as viewed from the sidethereof is located forward of a rear end of the volute casing.

In backpack-type air-blowing working machine configured as above, theposition of the center of gravity of the backpack-type air-blowingworking machine as viewed from the rear thereof is located below therotation axis of the centrifugal fan, and the position of the center ofgravity of the backpack-type air-blowing working machine as viewed fromthe side thereof is located forward of the rear end of the volute casingThus, when an operator performs cleaning operation while carrying thebackpack-type air-blowing working machine on his/her back using shouldertraps, a weight of the backpack-type air-blowing working machine issupported by the lumbar region of the operator, and therefore thebackpack-type air-blowing working machine is stabilized, so that theoperator becomes less likely to fall down rearwardly, thereby making itpossible to more easily manipulate the air-blowing working machine toreduce fatigue of the operator.

Preferably, in the above backpack-type air-blowing working machine, thebattery pack is disassemblably assembled onto a support rack portionprovided to extend rearwardly and horizontally from a lower end of theback plate portion of the backpack frame and located just beneath thevolute casing. This makes it possible to facilitate a charging operationfor the battery pack to increase operating efficiency. Further, inimplementation of the present invention, the battery pack may becomposed of a plurality of rechargeable battery packs. Each of theplurality of rechargeable battery packs is connected to the electricmotor, and each of the plurality of rechargeable battery packs isassembled in a manner that allows for disassembly of the respectivebattery pack from the electric motor. In this case, it becomes possibleto enhance convenience of the backpack-type air-blowing working machineusing a battery pack standardly utilized in various electric tools andelectric gardening machines.

In implementation of the present invention, the backpack-typeair-blowing working machine is preferably configured such that, when itis placed on a horizontal mounting surface such that the back plateportion is in a standing posture, the back plate portion is kept in thestanding posture, in both of a state in which the battery pack isattached to the support rack portion of the backpack frame and a stateafter the battery pack is detached from the support rack portion. Inthis case, there is no need to support the backpack-type air-blowingworking machine by hand to maintain standing posture, before and afterattachment of the battery pack, so that it becomes possible tofacilitate the detaching and attaching operations for charging thebattery pack. Preferably, the volute casing is configured such that oneof opposite ends thereof in a rightward-leftward direction has a blowingtube portion formed to blow out air therefrom and communicated with andconnected to a blowing duct, and the other end thereof in therightward-left direction has a joint with respect to the battery pack.In this case, the blowing duct is disposed on the one end of the volutecasing in the rightward-leftward direction, and the battery pack isdisposed on the other end of the volute casing in the rightward-leftwarddirection, so that it becomes possible to provide good weight balance inthe rightward-leftward direction during use of the backpack-typeair-blowing working machine. Preferably, the backpack-type air-blowingworking machine is configured such that the position of the center ofgravity of the backpack-type air-blowing working machine as viewed fromthe rear thereof is located within a region extending from a center lineof the backpack frame in each of a rightward direction and a leftwarddirection, by a length of 10% of a maximum width of the backpack framein the rightward-leftward direction. In this case, it becomes possibleto prevent a load from being largely imposed on one of the right andleft shoulders of the operator carrying the backpack frame on the back.

In addition to the above backpack-type air-blowing working machine,according to other aspects of the present invention, there are providedthe following backpack-type air-blowing working machines. According to asecond aspect of the present invention, there is provided abackpack-type air-blowing working machine in which a pair of volutecasings arranged side-by-side in a forward-rearward direction andincorporating, respectively, a pair of centrifugal fans each configuredto be driven by a respective one of a pair of front and rear electricmotors arranged in a coaxial relation are assembled in an upstandingmanner to a backpack frame to be carried on e back of an operator usingshoulder straps during use. This backpack-type air-blowing workingmachine comprises a pair of rechargeable battery packs connected,respectively, to the electric motors, wherein the rechargeable batterypacks are detachably attached to the backpack frame, such that aposition of the center of gravity of the backpack-type air-blowingworking machine as viewed from the rear thereof is located below arotation axis of the centrifugal fans, and a position of the center ofgravity of the backpack-type air-blowing working machine as viewed fromthe side thereof is located forward of a rear end of the volute casing,and wherein airflows blown out from respective blowing ports of thevolute casings according to rotation of the centrifugal fans duringoperation of the electric motors are merged together and discharged froma blowing duct.

According to a third aspect of the present invention, there is provideda backpack-type air-blowing working machine including a pair of upperand lower volute casings. Each of the volute casings incorporate acentrifugal fan configured to be driven by an electric motor. Each ofthe volute casing is assembled in an upstanding manner to a backpackframe to be carried on the back of an operator using shoulder strapsduring use. This backpack-type air-blowing working machine comprises arechargeable battery pack connected to each of the electric motors,wherein the rechargeable battery pack is detachably attached to thebackpack frame, such that a position of the center of gravity of thebackpack-type air-blowing working machine as viewed from the rearthereof is located below an output shaft of the electric motor fordriving the centrifugal fan in the upper volute casing, and a positionof the center of gravity of the backpack-type air-blowing workingmachine as viewed from the side thereof is located forward of rear endsof the pair of upper and lower volute casings, and wherein airflowsblown out from respective blowing ports of the volute casings accordingto rotation of the centrifugal fans during operation of the electricmotor are merged together and discharged from a blowing duct.

In the backpack-type air-blowing working machines according the secondand third aspects of the present invention, a small-size fan may be usedas each of the pair of centrifugal fans configured to be driven,respectively, by two small-size electric motors. Thus, as compared to acase of using a large-size fan configured to be driven by a singlelarge-size electric motor, it becomes possible to reduce blowing noise,and obtain an airflow volume enough for cleaning by merging airflowsfrom the centrifugal fans arranged side-by-side in the forward-rearwardor upward-downward direction. Further, a pair of centrifugal fans eachconfigured to be driven by an independent electric motor areincorporated, respectively, in the pair of volute casings disposedside-by-side in the forward-rearward or upward-downward direction toform a pair of individual blower units, so that it becomes possible tosimplify assembling operation for the backpack-type air-blowing workingmachine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a backpack-type air-blowing working machineaccording to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of the backpack-type air-blowingworking machine depicted in FIG. 1, at a central position in arightward-leftward direction.

FIG. 3 is a rear view of the backpack-type air-blowing working machine,in a state after a cover depicted in FIG. 2 is detached.

FIG. 4 is a vertical sectional view of a backpack-type air-blowingworking machine according to a second embodiment of the presentinvention, at a central position in the rightward-leftward direction.

FIG. 5 is a horizontal sectional view depicting respective blowing tubeportions of a pair of front and rear volute casings depicted in FIG. 4.

FIG. 6 is a sectional view depicting a coupling portion between theblowing tube portions and a blowing duct depicted in FIG. 5.

FIG. 7 is a vertical sectional view depicting a modification of theblower unit of the backpack-type air-blowing working machine depicted inFIG. 4.

FIG. 8a is a left side view of a backpack-type air-blowing workingmachine according to a third embodiment of the present invention.

FIG. 8b is a rear view of e backpack-type air-blowing working machine inFIG. 8 a.

FIG. 9 is a vertical sectional view of the backpack-type air-blowingworking machine depicted in FIG. 8b , at a position of each rotationaxis thereof.

FIG. 10a is a left side view depicting backpack-type air-blowing workingmachine according to a fourth embodiment of the present invention.

FIG. 10b is a rear view of backpack-type air-blowing working machine inFIG. 10 a.

FIG. 11 is a vertical sectional view of the backpack-type air-blowingworking machine depicted in FIG. 10 b, at a position of each rotationaxis thereof.

FIG. 12a is a vertical sectional view of a backpack-type air-blowingworking machine according to another embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 12b is a vertical sectional view of a backpack-type air-blowingworking machine according to yet another embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 13a is a vertical sectional view of a backpack-type air-blowingworking machine according to still another embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 13b is a vertical sectional view of a backpack-type air-blowingworking machine according to yet still another embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 14 is a vertical sectional view of a backpack-type air-blowingworking machine according to another further embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 15a is a vertical sectional view of a backpack-type air-blowingworking machine according to yet a further embodiment of the presentinvention, at a position of each rotation axis thereof.

FIG. 15b is a vertical sectional view of a backpack-type air-blowingworking machine according to still a further embodiment of the presentinvention, at a position of each rotation axis thereof.

DESCRIPTION OF EMBODIMENTS

With reference to the accompanying drawings, a backpack-type air-blowingworking machine of the present invention will be described based onvarious embodiments thereof, wherein the same elements or componentswill be described by assigning the same reference sign thereto.

First Embodiment

As depicted in FIGS. 1 to 3, a backpack-type air-blowing working machine10 according to a first embodiment of the present invention comprises: abackpack frame 11 having a back plate portion 12 having a shapeconforming to the back of an operator (i.e., a user or a worker); aspiral-shaped volute casing 21 assembled in a standing manner to thebackpack frame 11 at a position rearward of the back plate portion 12; acentrifugal fan 22 rotatably pivoted within the volute casing 21; anelectric motor 23 assembled to the volute casing 21 and operable torotate the centrifugal fan 22; four (a plurality of) rechargeablebattery packs 40 detachably attached to the backpack frame 11 at aposition underneath the volute casing 21 and connected to the electricmotor 23; and a control device 41 for controlling driving of theelectric motor 23 and electric power feeding from the battery packs 40.In the first embodiment, a position of the center G of gravity of thebackpack-type air-blowing working machine 10 as viewed from the rearthereof is located below a rotation axis (central axis) 22 a of thecentrifugal fan 22, and a position of the center G of gravity of thebackpack-type air-blowing working machine 10 as viewed from the sidethereof is located forward of a rear end of the volute casing 21.

The backpack frame 11 is configured to be carried on the back of theoperator using shoulder straps 13. Each shoulder strap 13 is attached toa respective one of right and left ends of the back plate portions 12 ofthe backpack frame 11. The backpack frame 11 also has a support rackportion 14 integrally formed with the back plate portion 12 to extendhorizontally and rearwardly from a lower end of the back plate portion12, and the support rack portion 14 of the backpack frame 11 is formedwith an air introduction port 14 a for introducing therethrough air intoa blower unit 20 composed of the volute casing 21, the centrifugal fan22 and the electric motor 23. The blower unit 20 is configured to rotatethe centrifugal fan 22 in the volute casing 21 according to the electricmotor 23 to discharge air from a blowing port 21 c at a distal end of anaftermentioned blowing tube portion 21 b.

As depicted in FIG. 3, the volute casing 21 has a rear wall formed withan air suction port 21 a, and a right wall provided with a blowing tubeportion 21 b extending outwardly. A blowing port 21 c formed at a distalend of the blowing tube portion 21 b is communicated with and connectedto a blowing duct 30. As depicted in FIG. 2, the electric motor 23 isattached to a front wall of the volute casing 21. The centrifugal fan 22is fixed to an output shaft 23 a of the electric motor 23, within thevolute casing 21. In this embodiment, as the electric motor 23, an outerrotor-type electric motor is employed. By rotatably attaching thecentrifugal fan 22 to the output shaft 23 a of the electric motor 23integrally assembled to the front wall of the volute casing 21, theblower unit 20 is assembled in a standing manner, as a single unit, tothe backpack frame 11 through a coil spring 15 (vibration dampingmeans). In this embodiment, the centrifugal fan 22 is directly attachedto the output shaft 23 a of the electric motor 23, and the output shaft23 a of the electric motor 23 is disposed in coaxial relation to therotation axis 22 a of the centrifugal fan 22. The battery packs 40 andthe control device 41 are mounted to the support rack portion 14 of thebackpack frame 11 located just beneath the blower unit 20, as mentionedbelow.

As depicted in FIG. 1, the blowing duct 30 connected to the blowing port21 c of the volute casing 21 comprises a flexible duct 32 connected to adistal end of an elbow duct 31, and a straight duct 33 connected to adistal end of the flexible duct 32. A grip 34 to be gripped by anoperator is attached to the straight duct 33, and a nozzle is attachedto a distal end of the straight duct 33. During cleaning operation, anoperator can manipulate the blowing duct 30 so as to direct the distalnozzle of the blowing duct 30 in a desired direction gripping the grip34.

As depicted in FIGS. 2 and 3, on an upper surface of a rear end of thesupport rack portion 14 of the backpack frame 11, four joints(attachments) 16 for joining the battery packs 40 thereto are arrangedside-by-side in a rightward-leftward direction. Through a slidingmovement in forward-rearward direction, each of the battery packs 40 isdetachably joined to a respective one of the joints 16. As each of thebattery packs 40, it is possible to employ a type of battery pack isrechargeable by a battery charger (not depicted), in a state after it isdetached from the joint 16, and commonly usable as a power supply forother electric gardening machines and various electric tools.

The control device 41 is disposed on an upper surface of a front end ofthe support rack portion 14 of the backpack frame 11. The control device41 is operable to control driving of the electric motor 23 and controlelectric power feeding from the battery packs 40 to the electric motor23. As depicted in FIGS. 1 and 2, the backpack frame 11 is provided witha cover 42 which covers the blower unit 20 and the control device 41,and the battery packs 40 are attached to the support rack portion 14 ofthe backpack frame 11 at positions outside the cover 42. The cover 42 isdetachably attached to the backpack frame 11 so as to enable the blowerunit 20 and the control device 41 be subjected to maintenance.

During use of the backpack-type air-blowing working machine 10configured as above, an operator carries the backpack frame 11 onhis/her back by putting the shoulder straps 13 over his/her shoulders,and starts to drive the electric motor 23 by electric power fed from thebattery packs 40. Thus, the centrifugal fan 22 is rotated within thevolute casing 21, and air sucked from the air suction port 21 a into thevolute casing 21 is discharged from the blowing port 21 c into theblowing duct 30 and finally blown out from the distal nozzle of theblowing duct 30 toward the ground. Thus, the operator can move thedistal nozzle of the blowing duct 30 in the rightward-leftward directionwhile gripping the grip 34 so as to blow and collect fallen leavesspread over the ground in a wide range.

The above backpack-type air-blowing working machine 10 is configuredsuch that the electric motor 23 is driven by electric power fed from thebattery packs 40. Thus, depending on mounting positions of the electricmotor 23 and the four battery packs 40 to be mounted as heavy loads tothe backpack frame 11, a difference arises in terms of usability orfatigue level in a situation where an operator performs cleaningoperation while carrying the backpack-type air-blowing working machine10 on his/her back. In this regard, the present inventors hasascertained that, when a position of the center of gravity of thebackpack-type air-blowing working machine 10 is located close to anoperator at a lower position as much as possible, it is possible toimprove usability of the backpack-type air-blowing working machine 10and reduce fatigue of the operator.

In the first embodiment configured by taking into account the abovematter, the volute casing 21 is disposed in a standing manner rearwardof the back plate portion 12, in such a manner that an axis of a voluteof volute casing 21 is located in orthogonal relation to the back plateportion 12. In this way, a length of the backpack frame 11 in theforward-rearward direction is reduced to enable the volute casing 21 tobe disposed at a position closer to the back of an operator. Further, inthe first embodiment, the electric motor 23 as a heavy load is fixed tothe front wall of the volute casing 21 so as to conic close to the backof an operator. Furthermore, in the first embodiment, the battery packs40 are assembled, respectively, to the joints 16 on the support rackportion 14 formed to extend rearwardly and horizontally from the lowerend of the back plate portion 12 of the backpack frame 11 and locatedjust beneath the volute casing 21, in such a manner as to bedisassemblable in the forward-rearward direction.

Thus, in the backpack-type air-blowing working machine 10 according tothe first embodiment, in a state in which an operator stands whilecarrying the backpack-type air-blowing working machine 10 on his/herback, a position of the center G of gravity of the backpack-typeair-blowing working machine 10 as viewed from the rear thereof islocated below the rotation axis 22 a of the centrifugal fan 22, and aposition of the center G of gravity of the backpack-type air-blowingworking machine 10 as viewed from the side thereof is located forward ofthe rear end of the volute casing 21, particularly, in the firstembodiment, located forward of a center line Cf of the volute casing 21in the forward-rearward direction, as depicted in FIGS. 2 and 3. It hasbeen ascertained that when an operator performs cleaning operation whilecarrying the backpack-type air-blowing working machine 10 on his/hershoulder using the shoulder straps 13, a weight of the backpack-typeair-blowing working machine 10 is supported by the lumbar region of theoperator, and therefore the backpack-type air-blowing working machine 10is stabilized, so that the operator becomes less likely to rearwardly,thereby making it possible to more easily manipulate the air-blowingworking machine 10 to reduce fatigue of the operator. In this way, evenwhen an operator performs cleaning operation while carrying thebackpack-type air-blowing working machine 10 on his/her back, it becomespossible to prevent the shoulder straps 13 from be put over theshoulders of the operator in such a manner as to pull the operatorrearwardly, and thus enable the operator to become less likely to falldown rearwardly and thus become less likely to fatigue.

In the first embodiment, in charging operation for the battery packs 40,the battery packs 40 can be detached from the support rack portion 14without detaching, from the backpack frame 11, the cover 42 covering theblower unit 20 and the control device 41, so that it becomes possible todetach the battery packs 40 without taking time and effort for detachingthe cover 42.

In the first embodiment, when the backpack-type air-blowing workingmachine 10 is placed on a horizontal mounting surface such that the backplate portion 12 is in a standing posture, the back plate portion 12 iskept in the standing posture, in both of the state in which the batterypacks 40 are attached to the support rack portion 14 of the backpackframe 11 and the state after the battery packs 40 are detached from thesupport rack portion 14. Thus, there is no need to support thebackpack-type air-blowing working machine 10 by hand to maintain thestanding posture, before and after attachment of the battery packs 40,so that it becomes possible to facilitate the detaching and attachingoperations for charging the battery packs 40.

In the first embodiment, the position of the center G of gravity of thebackpack-type air-blowing working machine 10 as viewed from the rearthereof is located within a region Cw extending from a center line C ofthe backpack frame 11 in each of a rightward direction and a leftwarddirection, by a length of 10% of a maximum width of the backpack frame11 in the rightward-leftward direction, so that it becomes possible toprevent a load from being largely imposed on one of the right and leftshoulders of the operator carrying the backpack frame 11 on his/herback. Further, in the first embodiment, respective sets of the four(plurality of) joints 16 and the four (plurality of) battery packs 40are equally divided into two and arranged on both sides of a center lineof the backpack frame 11 in the rightward-leftward direction. This makesit possible to provide good weight balance in the rightward-leftwarddirection of the backpack-type air-blowing working machine 10.

Second Embodiment

As depicted in FIGS. 4 to 6, in a backpack-type air-blowing workingmachine 10 according to a second embodiment of the present invention, apair of front and rear volute casings 21A, 21B internally provided,respectively, with a pair of centrifugal fans 22A, 22B each configuredto be driven by a respective one of a pair of front and rear electricmotors 23A, 23B arranged in coaxial relation are assembled in a standingmanner to a backpack frame 11. Positions of the rear volute casing 21Band the rear centrifugal fan 22B are also shown in FIG. 3.

As depicted in FIG. 4, the first electric motor 23A is integrallyassembled to a rear wall of the front-side first volute casing 21A, andthe first centrifugal fan 22A is rotatably attached to an output shaft23Aa of the first electric motor 23A within the first volute casing 21A,to form a first blower unit 20A. As depicted in FIGS. 4 and 5, the firstvolute casing 21A has a front wall formed with an air suction port 21Aa,and a right wall provided with a blowing tube portion 21Ab serving as aspiral-shaped outer distal end. The second electric motor 23B isintegrally assembled to a front wall of the rear-side second volutecasing 21B, and the second centrifugal fan 22B is rotatably attached toan output shaft 23Ba of the second electric motor 23B within the secondvolute casing 21B, to form a second blower unit 20B. As depicted in FIG.5, the second volute casing 21B has a rear wall formed with an airsuction port 21Ba, and a right wall provided with a blowing tube portion21Bb serving as a spiral-shaped outer distal end. Respective blowingports 21Ac, 21Bc of the first and second volute casings 21A, 21B arecommunicated with and connected to an elbow duct 31 of a blowing duct 30so as to enable airflows discharged from the blowing tube portions 21Ab,21Bb to be merged together and discharged thereinto.

The first volute casing 21A is formed such that a spiral-shaped airpassage is gradually expanded toward the blowing port 21Ac. Morespecifically, it is formed such that, toward the blowing port 21Ac, aspiral-shaped air passage is gradually expanded rearwardly in an axialdirection of a volute of the first volute casing 21A. The second volutecasing 21B is formed such that a spiral-shaped air passage is graduallyexpanded toward the blowing port 21Bc. More specifically, it is formedsuch that, toward the blowing port 21Bc, the spiral-shaped air passageis gradually expanded forwardly in an axial direction of a volute of thesecond volute casing 21B. As above, the first and second volute casings21A, 21B are displaced to gradually come closer to each other in theaxial direction, toward the blowing ports 21Ac, 21Bc, and respectivedistal ends of the blowing tube portions 21Ab, 21Bb of the first andsecond volute casings 21A, 21B are communicated with and connected to aninlet region 31 a of the blowing duct 30.

In the first embodiment, the blowing tube portions 21Ab, 21Bb of thefirst and second volute casings 21A, 21B are displaced to gradually comecloser to each other in the axial direction, toward the blowing ports21Ac, 21Bc, airflows discharged from the blowing tube portions 21Ab,21Bb are merged such that a discharge direction of air blown out fromthe blowing port 21Ac of the blowing tube portion 21Ab and a dischargedirection of air blown out from the blowing port 21Bc of the blowingtube portion 21Bb intersect each other at an angle θ of 5° (see FIG. 6).

As with the first embodiment, the volute casing 21A is fixed to a backplate portion 12 through a coil spring 15, so that the first blower unit20A is elastically supported by the backpack frame 11. Further, thesecond electric motor 20B is coaxially fixed to the first electric motor23A, so that the second blower unit 20B is elastically supported by thebackpack frame 11 through the first blower unit 20A.

Battery packs 40 for feeding electric power to the electric motors 23A,23B are attached onto a support rack portion 14 formed to extendrearwardly and horizontally from a lower end of the back plate portion12 of the backpack frame 11 and located just beneath the volute casings21A, 21B, in such a manner as to be detachable in a frontward-rearwarddirection, as with the first embodiment. A control device 41 forcontrolling driving of the electric motors 23A, 23B is also attached toan upper surface of a front end of support rack portion 14. Remainingmajor structures are the same as those in the first embodiment.

The backpack-type air-blowing working machine 10 according to the secondembodiment configured such that air is blown by the first centrifugalfan 22A, and the second centrifugal fan 22B which is a separatecomponent from the first centrifugal fan 22A, and respective airflowsfrom the first and second centrifugal fans 22A, 22B are merged in theinlet region 31 a of the blowing duct 30. In the backpack-typeair-blowing working machine 10 according to the second embodiment, whenthe fan is reduced in size, it is possible to obtain a sufficientairflow volume by the two centrifugal fans 22A, 22B, while reducingblowing noise as compared to the case of using a single large fan.Further, the backpack-type air-blowing working machine 10 according tothe second embodiment comprises the first electric motor 23A forrotating the first centrifugal fan 22A, and the second electric motor23B for rotating the second centrifugal fan 22B. This makes it possibleto facilitate reduction in size of each of the first and second electricmotors 23A, 23B and keep down driving noise generated from the first andsecond electric motors 23A, 23B as compared to the case of using asingle large fan to rotate the first and second centrifugal fans 22A,22B.

The backpack-type air-blowing working machine 10 according to the secondembodiment is configured such that airflows blown out from the blowingports 21Ac, 21Bc of the first and second volute casings 21A, 21B of thefirst and second blower units 20A, 20B are merged in the inlet region 31a of the blowing duct 30 and then discharged. In the second embodiment,the angle θ defined by a course direction of air discharged from theblowing port 21Ac of the first volute casing 21A and a course directionof air discharged from the blowing port 21Bc of the second volute casing21B is set to 5° so as to allow the two course directions to becomemaximally close to parallel relation. This makes it possible to reduce asituation where respective airflows blown out from the blowing ports21Ac, 21Bc of the first and second volute casings 21A, 21B collide witheach other to cause a reduction in airflow volume. It should be notedthat the angle θ defined by the course direction of air discharged fromthe blowing port 21Ac of the first volute casing 21A and the coursedirection of air discharged from the blowing port 21Bc of the secondvolute casing 21B is not limited to 5°, but may be appropriately set inthe range of 5° to 45°. In this case, it is also possible to obtain arequired effect.

In the backpack-type air-blowing working machine 10 according to thesecond embodiment, the electric motors 23A, 23B as heavy loads arearranged as forward as possible to come close to the back of anoperator, and the battery packs 40 are assembled onto the support rackportion 14 of the backpack frame 11 in such a manner as to bedisassemblable in the forward-rearward direction, as with the firstembodiment. In a state in which an operator stands while carrying thebackpack-type air-blowing working machine 10 on his/her back, a positionof the center G of gravity of the backpack-type air-blowing workingmachine 10 as viewed from the rear thereof is located below respectiverotation axes 22Aa, 22Ba of the centrifugal fans 22A, 22B, and aposition of the center G of gravity of the backpack-type air-blowingworking machine 10 as viewed from the side thereof is located forward ofa rear end of the rear-side second volute casing 21B, particularly, inthe second embodiment, located forward of a center line Cf of therear-side second volute casing 21B in the forward-rearward direction.(Although FIG. 3 is a rear view of the backpack-type air-blowing workingmachine 10 according to the first embodiment, the backpack-typeair-blowing working machine 10 according to the second embodiment can bedepicted in the same manner as that in FIG. 3. Thus, the reference signsin the second embodiment are added to corresponding reference signs inFIG. 3 in brackets.) It has been ascertained that when an operatorperforms cleaning operation while carrying the backpack-type air-blowingworking machine 10 on his/her shoulder using the shoulder straps 13, itbecomes possible to prevent the shoulder straps 13 from be put over theshoulders of the operator in such a manner as to pull the operatorrearwardly, and thus enable the operator to become less likely to falldown rearwardly and thus become less likely fatigue. Remainingfunctions/effects are the same as those in the first embodiment.

As depicted in FIG. 7, in a modification of the backpack-typeair-blowing working machine 10 according to the second embodiment, thefirst blower unit 20A and the second blower unit 20B each lying in ahorizontal posture are arranged one-above-the-other, and assembled tothe backpack frame 11. In this case, the air suction port 21Aa isprovided in an upper wall of the first blower unit 20A, and the airsuction port 21Ba is provided in a lower wall of the second blower unit20B. Remaining structures are substantially the same as those in thesecond embodiment.

Third Embodiment

As depicted in FIGS. 8a, 8b and 9, a backpack-type air-blowing workingmachine 10 according to a third embodiment of the present invention ischaracterized in that a first blower unit 20A and a second blower unit20B are arranged one-above-the-other at a position behind anaftermentioned back plate portion 12. In the third embodiment, the firstblower unit 20A and the second blower unit 20B are arrangedone-above-the-other at a position offset rightwardly from a center lineof a back plate portion 12 of a backpack frame 11 in arightward-leftward direction (see FIG. 8b ), in order to achieve aweight balance when aftermentioned battery packs 40 are arrangedside-by-side in an upward-downward direction, in a left end region ofback plate portion 12.

As depicted in FIG. 9, a first electric motor 32A is integrallyassembled to a front wall of an upper-side first volute casing 21A, anda first centrifugal fan 22A is rotatably attached to an output shaft23Aa of the first electric motor 23A within the first volute casing 21A,to form the first blower unit 20A. Similarly, a second electric motor23B is integrally assembled to a front wall of a lower-side secondvolute casing 21B, and a second centrifugal fan 22B is rotatablyattached to an output shaft 23Ba of the second electric motor 23B withinthe second volute casing 21B, to form the second blower unit 20B.

As depicted in FIGS. 8a, 8b and 9, each of the first and second volutecasings 21A, 21B has a rear wall formed with an air suction port (21Aa,21Ba), and a right wall provided with a blowing tube portion (21Ab,21Bb) serving as a spiral-shaped outer distal end. Respective blowingports 21Ac, 21Bc of the first and second volute casings 21A, 21B arecommunicated with and connected to an inlet region 31 a of a blowingduct 30, respectively, through a first connection duct 24A and a secondconnection duct 24B, so that airflows discharged from the blowing tubeportions 21Ab, 21Bb are merged together through the first and secondconnection ducts 24A, 24B, and introduced into the blowing duct 30.

In the left end region of the back plate portion 12, four joints(attachments) 16 for four battery packs 40 are arranged side-by-side inthe upward-downward direction. Through a sliding movement in aforward-rearward direction, each of the battery packs 40 is detachablyattached to a respective one of the joints 16. The four battery packs 40are detachably attached, respectively, to the joints 16 of the backpackframe 11, at positions outside a cover 42. Further, the four batterypacks 40 is attached to the left end region of the back plate portion 12in order to achieve a weight balance in the rightward-leftwarddirection, with respect to the blowing duct 30 communicated with andconnected to the blowing ports 21Ac, 21Bc of the first and second volutecasings 21A, 21B on a right side of the backpack frame 11.

In the backpack-type air-blowing working machine 10 according to thethird embodiment, the electric motors 23A, 23B assembled to the firstand second volute casings 21A, 21B are arranged just behind the backplate portion 12, and the battery packs 40 are arranged below a rotationaxis 22Aa of the upper-side first centrifugal fan 22A. Thus, a positionof the center G of gravity of the backpack-type air-blowing workingmachine 10 as viewed from the rear thereof is located below the rotationaxis 22Aa of the upper-side first centrifugal fan 22A, and a position ofthe center G of gravity of the backpack-type air-blowing working machine10 as viewed from the side thereof is located forward of rear ends ofthe first and second volute casings 21A, 21B, particularly, in the thirdembodiment, located forward of a center line Cf of the first and secondvolute casings 21A, 21B in the forward-rearward direction. In this way,even when an operator performs cleaning operation while carrying thebackpack-type air-blowing working machine 10 on his/her back, it becomespossible to prevent shoulder straps 13 from be put over the shoulders ofthe operator in such a manner as to pull the operator rearwardly,thereby facilitating the cleaning operation. In the third embodiment,the position of the center G of gravity of the backpack-type air-blowingworking machine as viewed from the rear thereof is located within aregion Cw extending from a center line C of the backpack frame 11 ineach of a rightward direction and a leftward direction, by a length of10% of a maximum width of the backpack frame 11 in therightward-leftward direction, so that it becomes possible to prevent aload from being largely imposed on one of the right and left shouldersof the operator carrying the backpack frame 11 on the back.

In the third embodiment, when the backpack-type air-blowing workingmachine 10 is placed on a horizontal mounting surface such that the backplate portion 12 is in a standing posture, the hack plate portion 12 iskept in the standing posture, in both of a state in which the batterypacks 40 are attached to the joints 16 of back plate portion 12 of thebackpack frame 11 and a state after the battery packs 40 are detachedfrom the joints 16 of the back plate portion 12. Thus, there is no needto support the backpack-type air-blowing working machine 10 by hand tomaintain the standing posture, before and after attachment of thebattery packs 40, so that it becomes possible to facilitate thedetaching and attaching operations for charging the battery packs 40.

In the backpack-type air-blowing working machine 10 according to thethird embodiment, each of the volute casings 21A, 21B has a respectiveblowing tube portion 21Ab, 21Bb for blowing out air, on a right sidethereof as one side in the rightward-leftward direction, and the blowingduct 30 is communicated with and connected to the blowing tube portion21Ab, 21Bb. On the other hand, the joints 16 for the battery packs 40are provided on a left side of the backpack frame 11 as the other sidein the rightward-leftward direction. That is, the blowing duct 30 isdisposed on the right side as one side in the rightward-leftwarddirection, and the battery packs 40 are arranged on the left side as theother side in the rightward-leftward direction, so that becomes possibleto provide good weight balance in the rightward-leftward directionduring use of the backpack-type air-blowing working machine 10.

In the backpack-type air-blowing working machine 10 according to thethird embodiment, airflows blown out from the blowing ports 21Ac, 21Bcof the first and second volute casings 21A, 21B of the first and secondblower units 20A, 20B are merged in the inlet region 31 a of the blowingduct 30 through the first and second connection ducts 24A, 24B, and thendischarged. In the third embodiment, an angle θ defined by a coursedirection of air discharged from the blowing port 21Ac of the firstvolute casing 21A and a course direction of air discharged from theblowing port 21Bc of the second volute casing 21B is set to 45°. Thismakes it possible to reduce a situation where respective airflows blownout from the blowing ports 21Ac, 21Bc of the first and second volutecasings 21A, 21B collide with each other to cause a reduction in airflowvolume. As regards other functions/effects, it is possible to obtain thesame functions/effects as those in the second embodiment.

Fourth Embodiment

As depicted in FIGS. 10a, 10b and 11, in a backpack-type air-blowingworking machine 10 according to a fourth embodiment of the presentinvention, a first blower unit 20A and a second blower unit 20B arearranged one-above-the-other at a position behind a back plate portion12, as with the third embodiment. Further, the lower-side second blowerunit 20B is disposed offset rearwardly from the first blower unit 20A soas to eliminate interference or contact between a lower portion of theupper-side first blower unit 20A and an upper portion of the lower-sidesecond blower unit 20B, and the upper-side first blower unit 20A isdisposed at a lower position than that in the third embodiment. In thefourth embodiment, the first blower unit 20A and the second blower unit20B are arranged rearwardly as compared to the position in the thirdembodiment. Thus, a plurality of battery packs 40 can be arranged tocome close to a central region of the back plate portion 12. Further,the first blower unit 20A and the second blower unit 20B are arranged inan overlapping manner in the upward-downward direction, so that an angleθ defined by a course direction of air discharged from a blowing port21Ac of a first volute casing 21A and a course direction of airdischarged from a blowing port 21Bc of a second volute casing 21B can beset to 8.5°. Thus, the angle θ can be reduced to a smaller value thanthat in the third embodiment. This makes it possible to reduce thesituation where respective airflows blown out from the blowing ports21Ac, 21Bc collide with each other to cause a reduction in airflowvolume, more effectively as compared to the third embodiment. As regardsother functions/effects, it is possible to obtain the samefunctions/effects as those in the third embodiment.

Other Embodiments

In implementation of the present invention, as in a modification of thebackpack-type air-blowing working machine 10 according to the fourthembodiment depicted in FIG. 12a , each of the first and second blowerunits 20A, 20B may be turned back-to-front, and the upper-side firstblower unit 20A may be disposed forward of the lower-side second blowerunit 20B, i.e., the lower-side second blower unit 20B may be disposedrearward of the upper-side first blower unit 20A. Alternatively, as inanother modification depicted in FIG. 12b , the upper-side first blowerunit 20A may be disposed rearward of the lower-side second blower unit20B, i.e., the lower-side second blower unit 20B may be disposed forwardof the upper-side first blower unit 20A.

Further, as depicted in FIG. 13a , the air suction port 21Aa of theupper-side first blower unit 20A may be disposed to face rearwardly, andthe air suction port 21Ba of the lower-side second blower unit 20B maybe disposed to face forwardly. In this case, each of the blowing tubeportions 21Ab, 21Bb of the first and second blower units 20A, 20Bextends downwardly, and each of the blowing ports 21Ac, 21Bc facesobliquely downwardly. In this modification, the angle θ defined by thecourse direction of air discharged from the blowing port 21Ac of thefirst volute casing 21A and the course direction of air discharged fromthe blowing port 21Bc of the second volute casing 21B is set in therange of 5° to 45°, and airflows discharged from the volute casings 21A,21B are merged in the inlet region 31 a of the blowing duct 30, so thatit becomes possible to suppress the possibility that respective airflowsblown out from the blowing ports 21Ac, 21Bc collide with each other.

Further, as depicted in FIG. 13b , a spiral direction of a volute in thevolute casing of the lower-side second blower unit 20B may be reversedto enable the blowing port 21Bc to face obliquely upwardly.

A backpack-type air-blowing working machine 10 according an embodimentdepicted in FIG. 14 is characterized in that a first blower unit 20A anda second blower unit 20B are arranged one-above-the-other at a positionbehind a back plate portion 12, and each of output shafts 23Aa, 23Ba offirst and second electric motors 23A, 23B each operable to drive arespective one of first and second centrifugal fans 22A, 22B is disposedto incline obliquely downwardly in a rearward direction at aninclination angle of 45°. In this embodiment, as with the aforementionedembodiments, a position of the center G of gravity of the backpack-typeair-blowing working machine 10 as viewed from the rear thereof islocated below a rotation axis 22Aa of the first centrifugal fan 22A, anda position of the center G of gravity of the backpack-type air-blowingworking machine 10 as viewed from the side thereof is located forward ofa center line of the first and second volute casings 21A, 21B in theforward-rearward direction, so that even when an operator performscleaning operation while carrying the backpack-type air-blowing workingmachine 10 on his/her back, it becomes possible to prevent shoulderstraps 13 from be put over the shoulders of the operator in such amanner as to pull the operator rearwardly, thereby facilitating thecleaning operation.

In implementation of the present invention, as depicted in FIG. 15a , afirst blower unit 20A and a second blower unit 20B may be arranged suchthat each of an air suction port 21Aa and an air suction port 21Bathereof faces forwardly and obliquely downwardly. Alternatively, asdepicted in FIG. 15 b, the first and second volute casings 21A, 21B maybe arranged such that each of the air suction ports 21Aa, 21Ba thereoffaces forwardly and obliquely upwardly. In these embodiments, each ofthe first and second blower units 20A, 20B is inclined by 45°. However,this inclination angle is not limited to 45°. Further, the first volutecasing 21A and the second volute casing 21B may be inclined,respectively, at different inclination angles.

In the above embodiments, it is desirable to avoid forming an opening inthe cover 42 if possible. Further, in the backpack frame 11, the backplate portion 12 is formed with an air introduction port 12 a, and thesupport rack portion 14 is formed with the air introduction port 14 a.Alternatively, only the support rack portion 14 is formed with the airintroduction port 14 a. In the case where only the support rack portion14 is formed with the air introduction port 14 a, a space defined by thebackpack frame 11 and the cover 42 is opened to the outside only via theair introduction port 14 a of the support rack portion 14, so that itbecomes possible to reduce noise to be felt by an operator. In the aboveembodiments, a sound absorption material may be provided on an innersurface of the cover 42, or a sound absorption material such as spongeor a sound absorption structure such as a silencer may be provided inthe first and second volute casings 21A, 21B or a blowing passage suchas the blowing duct 30. This makes it possible to further reduce noiseto be felt by an operator.

The functions/effects arising from the reductions in size of fan and theelectric motor, and the merging of airflows from the blowing ports,based on providing two blower units, i.e., the first and second blowerunits 20A, 20B, can be obtained in any other suitable type ofbackpack-type air-blowing working machine. For example, a fan is notlimited to a centrifugal fan, but an axial flow fan or a diagonal flowfan provided in a cylindrical casing may be used to obtain the samefunctions/effects. Further, in addition to a prime mover composed of anelectric motor, an engine-type prime mover composed of an internalcombustion engine may be used to obtain the same functions/effects.

1. A backpack-type air-blowing working machine comprising: a backpackframe having at least a back plate portion conformable to the back of anoperator, the backpack frame being configured to be carried on the backof the operator through the back plate portion using shoulder straps; avolute casing mounted to the backpack frame at a position rearward ofthe back plate portion, in such a manner that a center of a volute isset in a direction intersecting a planar direction of the back plateportion; a centrifugal fan rotatably supported within the volute casing;an electric motor assembled to the volute casing and operable to rotatethe centrifugal fan; and a rechargeable battery pack attached to thebackpack frame and operable to feed electric power to the electricmotor, wherein the backpack-type air-blowing working machine isconfigured such that a position of the center of gravity of thebackpack-type air-blowing working machine as viewed from a rear thereofis located below a rotation axis of the centrifugal fan, and a positionof the center of gravity of the backpack-type air-blowing workingmachine as viewed from a side thereof is located forward of a rear endof the volute casing.
 2. The backpack-type air-blowing working machineas recited in claim 1, wherein the backpack frame further has a supportrack portion provided to extend rearwardly from a lower end of the backplate portion and located just beneath the volute casing, and whereinthe battery pack is assembled onto the support rack portion in such amanner as to be disassemblable in a forward-rearward direction.
 3. Thebackpack-type air-blowing working machine as recited in claim 1, whereinthe backpack frame further has a support rack portion provided to extendrearwardly and horizontally from a lower end of the backpack frame andlocated just beneath the volute casing, and the battery pack is composedof a plurality of rechargeable battery packs, each of the plurality ofrechargeable battery packs is connected to the electric motor, and eachof the plurality of rechargeable battery packs is assembled onto thesupport rack in a manner that allows for disassembly of the respectivebattery pack from the electric motor in a forward-rearward direction. 4.The backpack-type air-blowing working machine as recited in claim 2,which comprises a cover covering the volute casing, the cover beingdetachably attached to the backpack frame in such a manner that thebattery pack assembled onto the support rack portion is located outsidethe cover.
 5. The backpack-type air-blowing working machine as recitedin claim 1, wherein the volute casing is configured such that one ofopposite ends thereof in a rightward-leftward direction has a blowingtube portion formed to blow out air therefrom and communicated with andconnected to a blowing duct, and the other end thereof in therightward-leftward direction has a joint with respect to the batterypack.
 6. The backpack-type air-blowing working machine as recited inclaim 5, wherein the battery pack is composed of a plurality ofrechargeable battery packs each of the plurality of rechargeable batterypacks is connected to the electric motor, the plurality of rechargeablebattery packs being arranged on one side of the back plate portion ofthe backpack frame in the rightward-leftward direction to extend in anupward-downward direction, and attached to the back plate portion insuch a manner that allows for disassembly of the respective battery packfrom the electric motor in a forward-rearward direction.
 7. Thebackpack-type air-blowing working machine as recited in claim 2, whichis configured such that, when the backpack-type air-blowing workingmachine is placed on a horizontal mounting surface such that the backplate portion is in a standing posture, the backpack-type air-blowingworking machine stands by itself while keeping the back plate portion inthe standing posture, in both of a state in which the battery pack isattached to the support rack portion and a state after the battery packis detached from the support rack portion.
 8. The backpack-typeair-blowing working machine as recited in claim 1, which is configuredsuch that the position of the center of gravity of the backpack-typeair-blowing working machine as viewed from the rear thereof is locatedwithin a region extending from a center line of the backpack frame ineach of a rightward direction and a leftward direction, by a length of10% of a maximum width of the backpack frame in the rightward-leftwarddirection.
 9. A backpack-type air-blowing working machine in which apair of volute casings arranged side-by-side in a forward-rearwarddirection and incorporating, respectively, a pair of centrifugal fanseach configured to be driven by a respective one of a pair of front andrear electric motors arranged in a coaxial relation are assembled in anupstanding manner to a backpack frame to be carried on the back of anoperator using shoulder straps during use, the backpack-type air-blowingworking machine comprising: a pair of rechargeable battery packsconnected, respectively, to the electric motors, wherein therechargeable battery packs are detachably attached to the backpackframe, such that a position of the center of gravity of thebackpack-type air-blowing working machine as viewed from the rearthereof is located below a rotation axis of the centrifugal fans, and aposition of the center of gravity of the backpack-type air-blowingworking machine as viewed from the side thereof is located forward of arear end of the volute casing, and wherein airflows blown out fromrespective blowing ports of the volute casings according to rotation ofthe centrifugal fans during operation of the electric motors are mergedtogether and discharged from a blowing duct.
 10. A backpack-typeair-blowing working machine in which a pair of upper and lower volutecasings each incorporating a centrifugal fan configured to be driven byan electric motor are assembled in an upstanding manner to a backpackframe to be carried on the back of an operator using shoulder strapsduring use, the backpack-type air-blowing working machine comprising: arechargeable battery pack connected to each of the electric motors,wherein the rechargeable battery pack is detachably attached to thebackpack frame, such that a position of the center of gravity of thebackpack-type air-blowing working machine as viewed from the rearthereof is located below an output shaft of the electric motor fordriving the centrifugal fan in the upper volute casing, and a positionof the center of gravity of the backpack-type air-blowing workingmachine as viewed from the side thereof is located forward of rear endsof the pair of upper and lower volute casings, and wherein airflowsblown out from respective blowing ports of the volute casings accordingto rotation of the centrifugal fans during operation of the electricmotor are merged together and discharged from a blowing duct.